We have developed a practical stereoretentive iodine/lithium‐exchange process that allows the stereodefined preparation of cis‐ and trans‐cycloalkyllithium compounds from their corresponding stereodefined iodides. Quenching with electrophiles offers stereospecific access to both cis‐ (up to 96 % cis) and trans‐cycloalkyl derivatives (up to 99 % trans). A detailed study of the thermodynamic stabilities
Asymmetric methylene transfer reactions I: Asymmetric synthesis of oxiranes from carbonyl compounds by methylene transfer reaction using chiral S-methyl-S-neomenthyl-N-tosyl sulfoximines
作者:Shabbirali S. Taj、Raghavan Soman
DOI:10.1016/0957-4166(94)80120-7
日期:1994.8
The use of ylides prepared from (−)-S-methyl-S-neomenthyl-N-tosyl sulfoximine, 10a, and its epimer at sulfur, 10b, as methylenetransfer reagents for the conversion of prochiral carbonyl compounds to oxiranes has yielded chiral oxiranes with 56–86% enantiomeric excess.